Fix alignment of the links in the BOX
Load OPKs at startup from the inotify thread

Loading OPKs can take a certain amount of time; loading them on
a thread makes the menu start much faster.
Maintain a list of objects in the box for faster access
When broadcasting a signal, don't send it to the caller object
Fix the START button / Return key launching the wrong link
Added key navigation
Added a HOWTO document to describe the interface with the themes
Select the first link of the menu by default